On 2010-05-02 12:48 , James Porter wrote:
On 5/2/2010 4:34 AM, Carl Banks wrote:
Why don't you use mysubtype.__new__(mysubtype,...)?
If you wrote mysubtype in C, and defined a different tp_new than
ndarray, then this exception will trigger. And it ought to; you don't
want to use ndarray's tp_new to create an object of your subclass, if
you've defined a different tp_new.
Unfortunately, I can't do that, since that call is in NumPy itself and
it's part of their "standard" way of making instances of subclasses of
ndarray. Functions like numpy.zeros_like use ndarray.__new__(subtype,
...) to create new arrays based on the shape of other arrays.
The Python version of the subclass is shown here:
<http://docs.scipy.org/doc/numpy/user/basics.subclassing.html#slightly-more-realistic-example-attribute-added-to-existing-array>,
and I'm trying to write something pretty similar in C. I'm trying to
stay in C since everything else is in C, so it's easier to stay in C
then to jump back and forth all the time.
Maybe the real answer to this question is "NumPy is doing it wrong" and
I should be on their list; still, it seems strange that the behavior is
different between Python and C.
Perhaps things would be clearer if you could post the C code that you've written
that fails. So far, you've only alluded at what you are doing using
Python-syntax examples.
--
Robert Kern
"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco
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